1. Field of the Invention
This invention relates to apparatus for agricultural tillage. The no-till row crop aerator is designed to be towed behind an agricultural tractor through established growing crops. Unlike conventional subsoil tilling machines, this invention's unique soil lifting action creates macrapores in the soil the entire width of the invention under the growing plants, causing increased aeration of the soil, with minimal soil surface disturbance.
2. Description of the Related Art
The conventional methods used in agriculture today consist of mainly three types of soil-working tools, i.e., the moldboard plow, the disc, and a variety of subsoil looseners.
Perhaps the most commonly used tool for plowing is the conventional moldboard plow. The plow bottom is typically set at a particular depth of plowing, for example, eight or ten inches. These plows are mounted to a main beam which is inclined relative to the direction of travel of a tractor so that each moldboard is set to take a strip of land, cut it, and roll the ground over into a furrow formed by the next forward moldboard. The leading moldboard turns its strip of ground over into a furrow formed on a previous pass of the plow system.
In the case where moldboard plows are used to till soil which has large amounts of trash (i.e., crop residue which, in the case of corn, may be bulky and tough) on the surface, a coulter may be located in front of each moldboard plow to cut through the trash and at least partially through the soil. This prevents a build-up of trash on the leading edges of the moldboard and further assists the moldboard in cutting the soil. Coulters are also used in connection with other tillage systems and are generally found in the form of a relatively flat, circular blade.
When a moldboard plow is used repeatedly to plow ground at the same depth, a layer of highly compacted soil is formed just beneath that depth. This is called the hard pan or plow sole. Furthermore, a moldboard plow displaces to one side all of the soil it has tilled. Eventually, the ground must be plowed in the opposite direction, and when this occurs, a deep side ridge normally is left at the end swath.
Another form of blade used in tillage systems is referred to as a "disc", which takes the shape of a dish or bowl. The edge of the disc blade is used to cut trash, while the concave surface of the blade is used to throw some of the top soil to the side. Typically, a plurality of disc blades are arranged at a relatively close spacing and mounted on a common shaft which extends at an acute angle relative to a line transverse of the direction of travel of the tractor. When a gang of disc blades is pulled across a field, complete coverage is obtained. That is, all of the soil is tilled, the trash is cut up and mixed with top soil, while some trash is buried. Complete coverage is obtained because the spacing of adjacent discs is typically about forty percent of the diameter of the disc, and the discs are turned slightly to work a path. In these devices, to reduce the effect of lateral soil displacement, a second line or gang of discs, facing the other direction, may be placed behind the first line. The effect of the disc blades is to work all of the soil, rather than selected strips. The disc is generally used in conjunction with the moldboard plow to prepare an appropriate seedbed for planting.
A major disadvantage of repeated use of the disc and plow is the formation of the hard pan or plow sole. Plant roots have difficulty penetrating the hard pan, thereby denying the plant access to extra nutrients and water. In addition, water has a tendency to drain over the hard pan, instead of being absorbed into the subsoils, thus resulting in increased water saturation of the topsoil. The drying process of the topsoil is delayed by this saturation, as the drying must be accomplished by evaporation of moisture from the surface instead of drainage deeper into the subsoil. The increased saturation of the topsoil delays the farmer's access to his fields. This causes the farmer's planting to be delayed, thereby generally resulting in a reduction of crop yields due to the shorter available growing period.
The subsoil loosening tools consist mainly of a series of parabolic shanks attached to a main frame. These shanks, which have hardened tips on the ends because of very high friction rates and excessive wear, work at depths of ten to twenty inches breaking through the hard pan or plow soles created by the moldboard plow or disc. The use of this tool is limited to fall tillage because of its working action of the soil. The ground surface is usually left very uneven due to the churning action caused by the wide frontal area of the shanks. The soil must be reworked in the spring with a disc or comparable soil working tool to prepare the soil for planting.
The main disadvantage associated with the aforementioned tillage methods is the inability to control erosion. When strips of land are rolled over by the moldboard plow or worked by the disc, there is very little trash left on the surface to absorb the impact of rainfall. When the soil, and not the trash, absorbs the great forces generated by rainfall, the soil is loosened and put into a liquid suspension, resulting in great soil erosion.
Another disadvantage associated with the aforementioned tillage methods is the high cost incurred in tilling the soil. In such cases, very large traction forces are necessary to force the soil working tools into the soil in order to obtain the required depth of penetration. Furthermore, the plowing, discing and planting of the soil are generally carried out in separate processes, thereby resulting in increased variable costs of production (i.e., diesel fuel, etc.) as well as fixed costs caused by shorter life span of equipment due to increased wear and tear.
As a result of the aforementioned disadvantages of conventional methods of agricultural tillage, an agricultural tillage system known as no-till or slot planting has evolved and is being used by an increasing number of farmers. In this method of crop production, crops are planted directly into crop residue without plowing or discing. No-till planting was made possible by the revision of existing planters, allowing them to plant seeds directly into the residue left by the previous year's crop. The planter consists of a double disc arrangment operating at approximately 11/2 inches in depth, creating a V-shaped slot in the soil surface. The seed is dropped into the slot, which is closed by two press wheels forcing the walls of the slot to collapse, thereby covering the seed and assuring good soil-to-seed contact for germination. Coulters, which are used on no-till planters to control the trash, are mounted directly in front of the double disc openers and operate at the same depth. The coulters cut through the trash, keeping the planter units from riding over the trash and leaving the seed on top of the trash, and not in the soil.
The main advantage associated with no-till planting is the ability to control soil erosion. By no-till planting, higher levels of residue are left on the surface, thereby helping to absorb the force of rainfall, thus decreasing soil erosion. In addition, more water can be absorbed into the subsoils, which water can then be used as reserves in the hot, dry growing months of summer. The highest rates of transpiration and evaporation occur during the summer months. If rainfall is minimal and roots cannot grow past the hard pan to reach water reserves, then the plants suffer, resulting in reduced yields.
No-till planting also results in lower costs and time savings. Because there is no requirement of multiple trips across the field to conduct different tillage processes, the cost of raising no-till crops is less than conventional methods. Another advantage of no-till planting is the increased proliferation of microbial life. By not shocking the soil with the use of discs or plows, microbial life flourishes.
The main disadvantage associated with no-till planting is that the crop yields are generally less than those yields associated with conventional tillage methods. The main reason for the decreased yields is that the soil transversed by no-till planting is less aerated than soil transversed by conventional tillage methods. As roots need oxygen for maximum growth to occur, the reduced amount of oxygen in the soil will result in reduced yields.
Examples of conventional agricultural tillage methods are described in the following patents
______________________________________ Patent Number Patent Date Patentees ______________________________________ 4,106,568 August 15, 1978 Cline 4,243,104 January 6, 1981 Sipos, Varga and Hali 4,245,706 January 20, 1981 Dietrich 4,403,662 September 13, 1983 Dietrich ______________________________________